ethylene vs propylene glycol anti-freeze

Jay · Oct 8, 2002

I was surfing Neo's website and looking at the coolant. They make a propylene glycol coolant (vs ethylene glycol most often found) that's very interesting. Here are some of the advantages they list for propylene glycol:
1.non-poisonous
2. cools better because it's not as dense
3. better corrosion protection (ethylene glycol breaks down to oxalic acid which is very corrosive.)

This is the short list of the advantages claimed for propylene glycol. It begs the question: why would anyone use ethylene glycol for anti-freeze?
Anybody know?

Dominic · Oct 8, 2002

Sierra antifreeze is propylene glycol - safe for the environment - same stuff they spray on frosted flakes to make them taste good

I stay away from the stuff for a regular antifreeze - it doesn't last very long, usually requires flushing every 6months to work well. I used it previously when I would winterize a Supra Conbrio inboard 351 boat - since I could then safely drain it without having to hardly recycle it (I could drink it and it wouldnt harm me in the least).

Sciguyjim · Oct 8, 2002

I tried propylene glycol antifreeze for a while. I'd heard that the black stuff that collects in the overflow tank was a decomposition product of ethylene glycol and prop gly wouldn't form that stuff. At first things looked fine but after 2 years, the black stuff began to reappear. I'd heard that the viscous prop gly didn't conduct heat quite as well as the thinner et gly, so I changed back to the et gly.

BTW, prop gly is relatively non toxic and can be ingested in small quantities but I wouldn't drink it. It doesn't taste too good anyway (and that's without all the additives.)

VaderSS · Oct 8, 2002

I tried it once.

It resulted in higher operating tems so I got rid of it.

I think it was due to less flow from the higher viscosity fluid.

dragboat · Oct 30, 2002

Quote:
"It begs the question: why would anyone use ethylene glycol for anti-freeze?
Anybody know?"

It is my understanding it protects aluminum parts from corrosion better for long term use especially with soft water "de-mineralized"

How much better I don't know but have heard this from several sources and even though they will run cooler with less water aluminum heads ect these engines need no less than a 60/40 mix for max protection in long term use.

MolaKule · Oct 30, 2002

You pose a good question, and I think coolant replacement before a two-year period
is a good practice; and always use deminerlized, or better yet, distilled water when you mix.

Cressida · Oct 30, 2002

Distilled water is fine for the battery but I don't think it is best to add to coolent.

I think the distilled water was a free ion, or something to that affect, which may cause it to attract atoms. Since aluminium is the "weaker" metal in the engine it tends to attract from the aluminum. Myself I just use fresh clear rain water for all my makeup water in my vehicles.

satterfi · Oct 30, 2002

quote:

Originally posted by Jay:
It begs the question: why would anyone use ethylene glycol for anti-freeze?
Anybody know?

Ethylene glycol is cheaper and works OK.

I use extended life antifreeze which is propylene gylcol based. It costs more but you don't have to change it as often.

Propylene gylcol also lubricates water pump seals better than ethylene glycol.

Al · Oct 31, 2002

quote:

Originally posted by Cressida:
Distilled water is fine for the battery but I don't think it is best to add to coolent.

I think the distilled water was a free ion, or something to that affect, which may cause it to attract atoms. Since aluminium is the "weaker" metal in the engine it tends to attract from the aluminum. Myself I just use fresh clear rain water for all my makeup water in my vehicles.

I'm really not a chemist-but I used to work in powerplant. All systems which required protection use demineralized water. I really don't buy your theory. (No offense). By experience-demineralized water works better than anything else in radiators. Also distilled water is many times less pure then demineralized/deionized water. There is carryover from the distillation process. I do know that from chemists in my former employment life.

Jay · Oct 31, 2002

satterfi, are you sure that your extended-life anti-freeze is propylene glycol based? I used Havoline extended-life coolant that was ethylene glycol.

satterfi · Oct 31, 2002

Jay

You're right, I got it backwards.

Neil Womack · Oct 31, 2002

I don't know about deionized/demineralized water being better than distilled.

A lifetime ago while serving as a Machinst Mate in the U S Navy we turn seawater into 0.002 ppm sodium free boiler feed water. Using a vacuum assited, steam heated distilling plant. And that was vintage WWII machinery.

Will a Reverse Osmosis with a deionizer do a better job than turning seawater into 0.002 ppm water.

Dominic · Nov 2, 2002

If you guys flush your systems fairly often anyways it really doesnt matter, distilled or deionized. I use distilled because its easy to find and cheap... 70/30 water/dexcool in the summer months and 50/50 for the winter for me.

carl97ss · Dec 4, 2002

Propylene glycol is a better absorber of heat from hot metal. If anyone noticed a higher coolant temp, after changing to Propylene/G from ethylene/G ,it could be because the P/G had absorbed more heat and ran at a higher temp.

JWRENCH · Dec 8, 2002

Propylene, Ethylene, distilled, demineralized? What ever happened to the good old days? You remember that movie Red Dawn? The ol' boys chevy got hot on him so they all got out and pee'd in the overflow tank, jumped right back in and chased down a few more commies.

MolaKule · Dec 8, 2002

Al is correct.

Distilled water has no minerals to coat metal or to interfere with the anti-freeze.

But in Red Dawn, they were desperate.

satterfi · Dec 9, 2002

quote:

Originally posted by carl97ss:
Propylene glycol is a better absorber of heat from hot metal. If anyone noticed a higher coolant temp, after changing to Propylene/G from ethylene/G ,it could be because the P/G had absorbed more heat and ran at a higher temp.

EG transfers heat better than PG.

For 50/50 mixtures,

PG has a slightly higher heat capacity, 5% higher, but EG more than makes up for that in heat transfer by having:

6% higher thermal conductivity
2% more dense
233% less viscous

These 3 properties are all more influence in heat transfer than heat capacity.

What you are seeing in higher coolant temperatures with PG is it's inability to reject heat as well as EG in the radiator.

msparks · Dec 9, 2002

More than you wanted to know about NPG Coolants:

http://www.evanscooling.com/main25.htm

INCREASES POWER
PROTECTS FROM BOIL-OVER
IMPROVES FUEL ECONOMY
PROVIDES LOW, OR NO-PRESSURE SYSTEM
ELIMINATES SYSTEM SCALING
ELIMINATES CORROSION
REDUCES DETONATION
ELIMINATES PUMP CAVITATION
REDUCES EMISSIONS
LENGTHENS LIFE OF ENGINE
EXTENDS RADIATOR LIFE
LIFE OF ENGINE COOLANT - 500,000 MILES
LENGTHENS LIFE OF COOLANT PUMP
PROLONGS HOSE LIFE
LOWERS MAINTENANCE COST
LESS ENGINE NOISE
ESSENTIALLY NON - TOXIC

ADDITIONAL NPG COOLANT BENEFITS TO AUTOMOTIVE MANUFACTURERS

REDUCES WARRANTY COSTS
OFFERS THERMAL MANAGEMENT FLEXIBILITY
MAKES POSSIBLE SMALLER, LIGHTER ENGINES
PERMITS USE MAGNESIUM ENGINES
OFFERS POSSIBILITY OF SMALLER RADIATOR OPENINGS
ALLOWS ALTERNATE LOCATIONS FOR RADIATOR
ENABLES CHOICES FOR FRONT-END PACKAGING
DECREASES COOLING SYSTEM PRESSURE

Evans NPG Coolant is 100% inhibited Propylene Glycol. It can maintain substantially vapor free, liquid - to - metal contact at all coolant temperature and engine loads. By bathing the entire combustion chamber with coolant 100% of the time, metal temperatures are controlled to such an extent that critical levels of detonation and pre-ignition are never reached. Because NPG’s naturally high 370 degree F boiling point, the need for adding high pressure to the cooling system is eliminated. Without pressure (or low pressure, i.e. 2 to 5 psi) in the system, gasket seals, hose connections, and even the radiator core, operate safer and longer. For a brief overview of the properties, please read our NPG properties tables found in our technical info page

satterfi · Dec 9, 2002

quote:

Originally posted by msparks:
More than you wanted to know about NPG Coolants:

Snip

That's interesting stuff. I wonder if the sales BS is correct.

How is it racers can use it? Most tracks don't let you run glycol in your bike. You get that stuff on the track and you have a lot of broken riders and bikes.

[ December 10, 2002, 02:13 PM: Message edited by: satterfi ]

msparks · Dec 10, 2002

quote:

Originally posted by satterfi:
[That's interesting stuff. I wonder if the sales BS is correct.

[/QB]

I supposed the information is correct: Here is an article in the Commercial Carrier Journal.

http://www.dieselsite.com/prodrev/evans_coolant1.htm

ethylene vs propylene glycol anti-freeze

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